body{font-family:Arial,Helvetica,sans-serif;margin:0;background:#f4f4f4}
header{background:#111;color:white;padding:20px}
nav{background:#333;padding:10px}
nav a{color:white;margin-right:15px;text-decoration:none}
main{padding:20px;background:white;max-width:900px;margin:auto}
footer{background:#111;color:white;padding:20px;text-align:center;margin-top:40px}